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implement Verifier;
#
# Copyright © 2004 Vita Nuova Holdings Limited
#
include "sys.m";
sys: Sys;
include "keyring.m";
kr: Keyring;
IPint: import kr;
include "bufio.m";
bufio: Bufio;
Iobuf: import bufio;
include "sexprs.m";
sexprs: Sexprs;
Sexp: import sexprs;
include "spki.m";
spki: SPKI;
Hash, Key, Cert, Name, Subject, Signature, Seqel, Toplev, Valid: import spki;
dump: import spki;
include "encoding.m";
base64: Encoding;
debug := 0;
init()
{
sys = load Sys Sys->PATH;
kr = load Keyring Keyring->PATH;
bufio = load Bufio Bufio->PATH;
sexprs = load Sexprs Sexprs->PATH;
spki = load SPKI SPKI->PATH;
base64 = load Encoding Encoding->BASE64PATH;
sexprs->init();
spki->init();
}
putkey(keys: list of ref Key, k: ref Key): list of ref Key
{
for(kl := keys; kl != nil; kl = tl kl)
if(k.eq(hd kl))
return keys;
return k :: keys;
}
keybyhash(h: ref Hash, keys: list of ref Key): ref Key
{
for(kl := keys; kl != nil; kl = tl kl){
k := hd kl;
if(k.hash != nil && h.eq(k.hash))
return k;
}
return nil;
}
verify(seq: list of ref Seqel): (ref Speaksfor, list of ref Seqel, string)
{
stack: list of ref Seqel;
keys: list of ref Key;
n0: ref Name;
cn: ref Cert;
delegate := 1;
tag: ref Sexp;
val: ref Valid;
for(; seq != nil; seq = tl seq){
pick s := hd seq {
C =>
diag := checkcert(s.c);
if(diag != nil)
return (nil, seq, diag);
if(stack != nil){
pick h := hd stack {
C =>
if(!delegate)
return(nil, seq, "previous auth certificate did not delegate");
if(!h.c.subject.principal().eq(s.c.issuer.principal))
return (nil, seq, "certificate chain has mismatched principals");
if(debug)
sys->print("issuer %s ok\n", s.c.issuer.principal.text());
}
stack = tl stack;
}
stack = s :: stack;
if(n0 == nil)
n0 = s.c.issuer;
cn = s.c;
pick t := s.c {
A or KH or O =>
delegate = t.delegate;
if(tag != nil){
tag = spki->tagintersect(tag, t.tag);
if(tag == nil)
return (nil, seq, "certificate chain has null authority");
}else
tag = t.tag;
if(val != nil){
if(t.valid != nil){
(ok, iv) := (*val).intersect(*t.valid);
if(!ok)
return (nil, seq, "certificate chain is not currently valid");
*val = iv;
}
}else
val = t.valid;
}
K =>
stack = s :: stack;
O =>
if(s.op == "debug"){
debug = !debug;
continue;
}
if(s.op != "hash" || s.args == nil || tl s.args != nil)
return (nil, seq, "invalid operation to `do'");
alg := (hd s.args).astext();
if(alg != "md5" && alg != "sha1")
return (nil, seq, "invalid hash operation");
if(stack == nil)
return (nil, seq, "verification stack empty");
pick h := hd stack {
K =>
a := h.k.hashed(alg);
if(debug)
dump("do hash", a);
keys = putkey(keys, h.k);
stack = tl stack;
C =>
;
* =>
return (nil, seq, "invalid type of operand for hash");
}
S =>
if(stack == nil)
return (nil, seq, "verification stack empty");
sig := s.sig;
if(sig.key == nil)
return (nil, seq, "neither hash nor key for signature");
if(sig.key.pk == nil){
k := keybyhash(sig.key.hash, keys);
if(k == nil)
return (nil, seq, "unknown key for signature");
sig.key = k;
}
pick c := hd stack {
C =>
if(c.c.e == nil)
return (nil, seq, "missing canonical expression for cert");
a := c.c.e.pack();
# verify signature ...
if(debug)
dump("cert a", a);
h := spki->hashbytes(a, "md5");
if(debug){
dump("hash cert", h);
sys->print("hash = %q\n", base64->enc(h));
}
failed := spki->checksig(c.c, sig);
if(debug)
sys->print("checksig: %q\n", failed);
if(failed != nil)
return (nil, seq, "signature verification failed: "+failed);
* =>
return (nil, seq, "invalid type of signature operand");
}
}
}
if(n0 != nil && cn != nil){
if(debug){
if(tag != nil)
auth := sys->sprint(" regarding %q", tag.text());
sys->print("%q speaks for %q%s\n", cn.subject.text(), n0.text(), auth);
}
return (ref Speaksfor(cn.subject, n0, tag, val), nil, nil);
}
return (nil, nil, nil);
}
checkcert(c: ref Cert): string
{
return nil;
}
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